Charged Particle (Negative Ion)-Based Cloud Seeding and Rain Enhancement Trial Design and Implementation

Round 1

Reviewer 1 Report

General Comments

This manuscript deals with an important weather modification project in China regarding rain enhancement using droplet charging. The manuscript describes the motivation, basic principle, location and instruments of the experiment planned, and three methods to evaluate the experiment performance. No results of the experiment are shown.

Despite the interest of the topic and the transcendence of the project results in case of success, the manuscript needs important improvements, both regarding form and content. For example I think the background should be expanded, incorporating research reported by Khain et al (2014), Hortal et al (2012) or the recent study by Chin et al (2019) – see references below. Moreover I think would be of interest, at least mentioning, the related process to the one described here regarding tower triggered lightning, as recently reported by Bech et al (2013) or Schultz et al (2018).

Regarding formal aspects, despite some parts of the manuscript are well written and only minor typos or corrections are needed, some other parts of the text need to be rewritten in depth to meet the standards of an international scientific journal; for example I think the expression “As is known to all (line 70)” is too colloquial, and also “When it comes to” (lines 135, 154). Regarding English use, contractions should also be avoided – see for example, in section 7.1, “there’re” (line 489), “it’s” (line 490) or there’s (line 504).

Other formal corrections include separation of values and units (for example 500mm -> 500 mm, in line 107).

In section 3.1. some ideas regarding the motivation of the study are repeated (already described in the introduction) and should be removed.

I also recommend reconsidering some of the figures. For example, Figure 11 can be removed as both panels are identical to Figure 10 and does not add relevant information. Similarly I suggest to group Figures 17 and 18 into a single figure, and I would do the same with Figure 19 and 20, group them into a new single one.

For all the above I recommend a major revision of the paper. Please consider both these general comments and also specific comments below (note that at this stage I do not intend to be exhaustive with English corrections, typos, etc. so please edit in depth the draft before a new submission).

 

Specific Comments

1. Page 1, line 16. Typo: operate.Lab -> operate. Lab
2. Page 1, line 20. Suggest: Thus it is of great significance and necessity -> Thus it is necessary
3. Page 1, line 21. Typo: characteristic -> characteristics
4. Page 2, line 33. Suggest (please check meaning): with -> regarding
5. Page 2, line 41. Suggest: Atmospheric humidity as a source of water -> Atmospheric humidity as a source of liquid water [Note that when you refer to atmospheric humidity you mean atmospheric water vapour, which is also water indeed, so I think it is necessary to add ‘liquid’ to the second form of water you refer later]
6. Page 6, line 236. Authors mention the concept of precipitation efficiency but it is not clear what do you mean; do you refer to the “precipitation-effectiveness index” as described by the AMS glossary? (see http://glossary.ametsoc.org/wiki/Precipitation-effectiveness_index). Please introduce the term properly.
7. Table 1, 2 should also list site altitudes – similarly to Tables 3 and 4. By the way check in Table 4 the rain gauge station numbers (10 gauges called ‘8’?).
8. Figure 17 and Figure 18 could be two panels of a unique figure. Similarly for Figure 19 and Figure 20.
9. Figure 21 should be enlarged to allow reading the labels.
10. Page 17, line 525. ‘climate conditions’ presumably you mean weather conditions, instead of climate conditions.
11. Page 17, line 526. Suggest : laws -> processes
12. Page 17, Table 7. Typo: (several times) Predicition. Moreover, are precipitation values in the table expressed in mm? Are they daily values?
13. Page 17, lines 523-543. The first two evaluation methods should be better explained, i.e. please give more details of the methodology proposed.
14. Page 17, line 547-548: “On the other hand, the ions will also affect the clouds and somehow can be detected with the help of Doppler radars and other observation equipments”. This is a very vague statement; besides Doppler radars operating in which frequency will be able to detect changes in clouds? Note that the usual operational Doppler radars operating in S, C or X bands are designed to detect precipitation rather than cloud particles. Please expand your comments.
15. References, line 619. Typo: check year

 

References

Bech, J., Pineda, N., Rigo, T., Aran, M., 2013. Remote sensing analysis of a Mediterranean thundersnow and low-altitude heavy snowfall event. Atmos. Res., 123, 305-322.

Chin, S. L., Guo, X., Xu, H., Kong, F., Xia, A., Zhao, H., ... & Ju, J. , 2019. An attempt to explain rain gush formation: the ionic wind approach. Plasma Research Express, 1(3), 035013.

Hortal, A. P., Garcia, S. E., & Caranti, G. M., 2012. Droplet charging by high voltage discharges and its influence on precipitation enhancement. Atmospheric research, 108, 115-121.

Khain, A., Arkhipov, V., Pinsky, M., Feldman, Y., & Ryabov, Y., 2004. Rain enhancement and fog elimination by seeding with charged droplets. Part I: Theory and numerical simulations. Journal of applied meteorology, 43(10), 1513-1529.

Schultz, C. J., Lang, T. J., Bruning, E. C., Calhoun, K. M., Harkema, S., Curtis, N., 2018. Characteristics of lightning within electrified snowfall events using lightning mapping arrays.  J. Geophys. Res. Atmos., 123.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear editor,

I found the paper by Zheng et al. interesting. The authors propose a methodology to enhance rain by charging cloud seeds. The paper is sufficiently well written but I think it could be improved.

The paper needs minor English improvement.

A main concern is given by their main result listed in Table 7 where the authors show the measured rainfall with a prediction based on historical data. The table is not clear. Which data from which regions are reported?

Moreover, the prediction must contain the mean and the standard deviation, and a statistical analysis (chi-squared test?) must be performed to compare measurements and predictions with their statistical variability to evaluate whether the methodology could be working.

Finally, may it be possible to provide a cost/benefit evaluation of the methodology?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Authors addressed my previous comments and I think the manuscript improved substantially. There are just minor issues that can addressed during the production stage.

Author Response

Thank you very much for your reviewing!

Reviewer 2 Report

Dear Editor,

I think that the authors have properly revised their paper as asked.

However, I was disoriented by the argument made at page 21 from line 633 to 643. They propose a F-test. However, after having written various equations, the actual test using their data is not performed. So the reader is left wondering about the result.

Thus I do not understand the logic of the argument. 

The authors should add the result of the test, or take off such a test proposal, or explain better their logic of proposing a statistical test but not evaluating it.

Author Response

Please see the attachment.

Author Response File: Author Response.docx